I'm installing Gentoo on an 800MHz G4 iBook. A problem that keeps cropping up is that if I leave it running for any length of time then it goes to sleep, with the screen failing to come back on when any keys are pressed. Is there any means of preventing it from doing this, perhaps something in /proc which may be changed?

Try turning off pbbuttonsd, I believe it's the culprit turning off your machine. Another option is that the machine is simply overheating, the PMU will turn off the machine itself in that case._________________Gentoo PPC FAQ: http://www.gentoo.org/doc/en/gentoo-ppc-faq.xml